Supervisory and control circuit for coded fire alarm systems



Sept. 25, 1951 N. E. RICHMOND 2,569,333

suPERvIsoRY AND coNTRoLRCIRcuIT FoR coman FIRE ALARM SYSTEMS Filed Dec. 29, 1949 2 Sheets-Sheet l H52. F551 f5.2 f 55.5

#557 v CONT/4675 /ww J0 6/ I Mf/ 3 5,

Sept. 25, 1951 N. E. RICHMOND 2,569,338

SUPERVISORY AND CONTROL CIRCUITVFOR CODED FIRE ALARM SYSTEMS Filed Deo. 29, 1949 2 Sheets-5heet 2 f'aented Sept. 25V, i951 N armani Richmond,

Shelby,0liio,1fas'signor to The Autocallompany, Shelby, .Ohi'oyz arcorpo- "ration-'of Ohio Applicationneceiuer 29, 14149, sriarNoz 135,639

' July 9, 1948, now abandoned.

The fpresentnvention has 'particular relation to fallt detecting means `forclosed circuit mas- -aItdeteeting means for detecting-fand-indicatling -an open, ide-energized for grounded circuit Aco'olitionin thefsystem.V

Y -Itfiscm-monpractice:to operatesysterns of athis l'type 'from a-l'conventional A- alternating curtrent Epower or light 'vl-'circuit 'as la power source.

"For example-*itis customaryfto use a sifxty cycle J'1j'1`0Jvoltlfsourcefior-@this purpose. Usually, ,such Ealtern'atingcurrent 4-'circ1iitsih'a-ye one -side Yor fthe "-neiitralfgroundedg Thus; thereisialwaysthe possikilityinf'a fre ala-rm @system-df lthe Ytype here 'lunderieonsiderationg Lof 'havingA a;y grounded #condition f'occur "in the #system circ-uit ylvviring nyhiehcouldcause far short circuit, 1 damaging the #c qipinentfor initiating a Ifalse start-of thereunding "inehanism #and-'ther'eby--- causing a false alar'intoibe :s'cundedyor making the system 'inoperative `without "giving-a trouble indication Luntil `ar-i'alarrn-is initiated. False operation-of 'fthe system ymay also -fresultfrom an vaccidental -opening'offthe re station Vcircuit. v -'--Accordingly, among the objects ofthisinvention are: to provide simple,'reliable and economlical f-nealns forI detecting andfsignalling `the -p'reslence-1o`f Ea ffaultinf'a Closed :circuit maste'rg'code 4type iirealarm lsyste'm; to employ# onl'yfoneLha-lf ofthe-alternating current Wave, obtained by the #use if fha-lf a wave rectifiers, *forlfthej purpose -of electrically -'s'upervising "all 0f the "Crlt's, the "supervising relays "ande the windirg`s'-f'of the 'nio- 'ito'r lonthe control panel; to `provide meansffor 3jr"34315lyingthe fother half wave of the-alter ating 'fcurfrentasfa-means rfor'initia'tingfthealar to *indi'atefas soon'f-a'sit occurs, anopen circuit EVor g ound inithefsystem, l or the 'failure -iofgth'e zpower siipply; to -maintainfde4energized-a control relay viliich, when energizedprevents 'operation of 'the vre bell f of :the nre alarmisystem' beyond fai predete'rfm'ined cycle-of their op`eration;' o control -theenergiaationofvthe icontrol LArelay"T loyftlie -aloplication of fillA Wave-alternating current and lto *control Ather ldeenergization :of *the `control @relay 'zhyzeith'erfshuntingi'd'own the Wind'ingfof -lsaidlfcon- Strol :relay Mby a Shalf `vvave rectifier 'connected across fthe 'Winding fof :said controlrrelay'whereain-:both said? control relay and '.rectierl are convenactedeinserieszwithanotherfhali vaveerectier,

(Omni-$367) vand saidrectifiers@are-connected toconduct the same l-ha-lf VJWave 4of@alternating Y current; -v-or by @blocking v`.the "pass-age -of `current through Lvthe -'co`ritro1-relay by a-rectiiier connected in series '5 #Withf-the'winding fsaid--control relay, butwith fthelatterfrectier connected in opposition'to another half wave rectierlso'that when onlyhalf wave alternating y:currentsis applied, current is J'hl'ockeidfrom passing through said control` relay; l0

thatshou-ld it fail# to 'operate j only the :limiting lcycle-offoperationiislost; to connect vthen/iridl"in-gs' of `a'larr'nf'relays "and winding'sof the'opler- "'atin'g'v electric '-m'o'tor in series circuit relay 'with various sectionsfof the fire kalarnrsystem Vso'that, as -long as 'the V circuit*continuityis maintained nand -circuitsjremain Iungrounded, the 4trouble -aia'rm ycontactsare'"held vOpen; land "to 'provide "an-- independently energized ftrouble alarm circu-itin' Wliichithe normally"open` alarmrelay 'con- `tactsfare connected.

Other objects of `this invention vx/ill, in part, vhe obvious and in part appear hereinafter.

Fora "more complete yunderstanding of :the 25 lnaltureand` scopel of this invention, reference' can lheihad Vto the 4following detail description, Itaken together with Ythe A7accompanying drawings in lwhich;

f'Figure 1 vis-a circuit diagram of `one embodi- 30 "ment of the invention;

'Figure v-2 `is `a 'circuit Adiagram Aof a modified embodiment lof the' invention; and

Figure `3 -is 'a fragmentary `circuit diagram illustrating themilliammeter in a diferentloca- 35 tioniin vlthe 'circuit .145 grounded vconductor fof a vpolyphase alternating Jcurrentfsystem. The alternating vsource l2 ris arranged to energize C`a closed circuit'rv master v'code Yfre Ialarm-system, the=detai1s :of Ywhich-will''l:1e fdescribedf-nowl f 1t willf' belobserved that thesystem 'includes lire `stations'v which are indica-ted atFSI through F84. It will beunderstood that a, larger A'or smaller number; of restations FS l through FS'd'may 'be employed as desired and that additional circuits L55 including- 'such*lirestations may beremployed within the scope of this invention. However, for purposes of `simplicity only four fire stations are shown in the drawing and a single circuit containing them is shown. It will be noted that each of the re stations includes normally open contacts I4 which are arranged to be closed to complete a circuit between conductors I5 and I6 which interconnect them in the event that an alarm is to be sounded and the conventional glass in a re station box is broken in order to sound the alarm. The conductor I5 which is looped through the various re stations to one side of each of the sets of contacts I4 therein terminates at TI and T4. In like manner the conductor I6 which is looped through the other contacts of the re boxes terminates at T2 and T3. The terminal TI is connected through a current limiting resistor RI to the line conductor or terminal IB. The purpose of the resistor Rl is to limit Ithe current ilow from the line conductor or terminal Il] in the event that the conductors I5 or I6, for example, should become grounded. The resistance of the current limiting resistor RI is such that, even if the terminal TI were grounded or connected directly to the other line conductor or terminal I I, the c-urrent flow therethrough would be of the order of one ampere.

With a view to indicating the condition of the conductor I5, its terminal T4 is connected to one terminal of a Iwinding I9 whichhas a high impedance and which forms a part of an alarm relay A. The relay A has contacts AI which are normally open as long as the `winding I9 is energized. As indicated, the contacts AI are connected to an alarm circuit which is energized independently. That is, the contacts AI are connected to energize a lamp or ring a bell or provide a like signal and the source of current therefor is -independent of the source I2 of alternating current. For example, a battery may be employed as the source of independent'energization for the alarm circuit to which the contacts AI `are connected. C

As illustrated in the drawing, the winding I9 of the alarm relay A is connected through a half wave rectifier HWRI'to a current limiting resistor 'R2 Iwhich is connected in series circuit relation with the windings 20 of fire alarm bells, four of ywhich are illustrated, generally, at FBI through FB4. The -resistor R2 is provided to limit the cur- `rent which can flow through the windings of the re bells FBI, etc., so as to provide the proper ringing current. It will be observed that the refsistor R2 is connected to a yterminal T5 and that the windings 20 are connected in series circuit relation by conductors 2|, 22 and 23. The r'- maining terminal of the Awinding 20 of the fire bell FB4 is connected to a terminal T6 which may be connected by a conductor 24 to an arma-ture 25 of a series motor, which has a series winding 26. The series motor forms a part of a code mechanism which is indicated, generally, at CM. A winding 2'I having a low impedance is connected in series with the series winding 26 of the series motor and constitutes a part of an alarm relay B. The alarm relay B has contacts BI that normally are held open as shown and, as illustrated, are connected to an alarm circuit which is energized independently and Vfunctions in the manner set forth above for alarm relay A. The winding 21 is connected by a conductor 28 to a milliammeter 29 which, in turn, is connected to the neutral or grounded line conductor or terminal II.

The conductor 24 also is connected through normally closed main contacts DI of a control relay, that is indicated generally at D, to the terminal T3 to which the conductor I6 is connected. The control relay D includes a winding 32 which normally is de-energized in a manner to be described presently. The circuit from conductor I6 and terminal T2 extends through a winding 33 of an alarm relay which is indicated, generally, at C. The alarm relay C has normally open contacts CI which, as shown, are connected to an alarm circuit that is independently energized and func-tions in the manner described above for the alarm relay A. A conductor 34 interconnects the winding 33 and oneside of a half wave rectier HWR2, this conductor 34 also being connected to one end of winding 32 of the control relay D. The other side of rectier HWR2 is connected by a conductor 35 to the milliammeter 29 which, in turnis ,connected to the neutral or grounded line conductor or terminal I I. The other end of winding 32 of control relay D is connected through conductor with a pair ofsealing or holding contacts D2 of relay D, and also with reset contacts 53 which are responsive to the code wheel.

It will be observed that the half wave rectiers HWRI and HWR2 are connected between the lineconductors or terminals In and II so that they are arranged to conduct the samehalf cycle of alternating current. Thus the circuit through these rectiers may be traced from the line conductor or terminal I0. resistor RI, conductor I5, winding I9, half wave rectifier HWRI, resistor R2, windings 20 of fire bells FBI through FB4, conductor 24, normally closed contacts DI, conductor I6, winding 33, conductor 34,`half wave rectifier HWR2, conductor and milliammeter 29 to the grounded or neutral line conductor or terminal II. Since the half waves of the same polarity are conducted by the rectiers HWRI and HWR2, Vand since the winding 32 is not in circuit, inasmuch as holding contacts D2 and reset contacts 5U`are open, no current flows through the winding 32 under normal supervising conditions and the control relay D remains de-energized and in the position shown in the drawing. In order to energize the winding 32 of control relay D, half waves of lopposite polarity of the alternating current are applied to it upon the closing of reset contacts 50, in a manner which lwill be described presently.

The code mechanism CM now will be described further. It will be observed that the armature 25 of the series Wound motor is arranged to drive a reduction gear train that is indicated, generally, at 36, the motor preferably being provided with an adjustable governor. The windings of such series motor can be electrically supervised Without the motor creeping, and such Emotor can have an easily adjusted speed control for obtaining a different speed or tempo of the Vcoded alarm to meet the requirements of diierent customers. A synchronous or shaded pole motor may be used instead of a series type motor if adjustable speed control is not required, as I shall later describe in connection with Figure 2. For illustrative purposes, the reduction gear train 36 is shown as comprising a pinion 31 and a gear wheel 38. However, it will be understood that these are shown and described solely for illustrative purposes and that the gear reduction actually may be obtained by using a, number Vof pinions and a number of gear wheels :as will be understood readily. The gear wheel .38` is arranged vto drive a code wheel 39 which has teeth 40 on its periphery drop. lIf this rectifier should become short circuited the code mechanism CM will run continuously after a re alarm signal has been s-tarted instead of stopping after four complete rounds of code. Y

In Figure 2, lI have illustrated a modiiied embodiment of my improved system. `In this embodiment, -I have illustrated a single phase, selfstarting synchronous motor or a shaded pole motor 25' for driving the code wheel 39 and the full-cycle contacts and rests contacts. These small synchronous or shaded pole motors are obtainable with built-in gear trains ofdiiferent ratios for obtaining practically any desired speed reduction v.at the power output shaft. For the average installation, I havesecured satisfactory performance withy a watt motor of this type, having an output speed of approximately 3 R. P. M. or 4 R. P. M., for driving the code wheel, etc., but it will be understood that if the requirements of different installations or different customers call for a higher or lower tempo ,of the coded alarm, it is a simple matter to substitute a different motor unit having the appropriate speed-reducing gear train for obtaining that higher or lower tempo of code signalling.

In this modied system of Figure 2, I have also shown a diiierent circuit arrangement for the winding 32 of control relay D and a different control of this relay involving a different location and operation of the seco-nd half-Wave rectier HWR2. In Figure 2, this rectifier HWR2 has been taken out of conductor 34, 35 and interposed in conductor 54, and has been arranged in opposition to the rst rectier HWRI, i. e. connected to oppose the half-Wave supervisory current which is transmitted through the rst rectier HWRI. Moreover, the upper end of the relayV winding 32 has been connected through a conductor 34 with the re station loop terminal T2, or upper end of alarm relay winding 33 instead of to the lower end thereof. Also, a third pair of con.acts D3 is arranged to contro1 an alarm circuit which is independently energized, similarly to the contacts AI, Bl and Cl of alarm relays A, B and C, this third pair of contacts D3 being normally open and being closed by the energization of control relay D.

The supervisory operation of the modified embodiment of Figure 2 is substantially the same as the supervisory operation of Figure 1. The

'lire station box loop l5, fire bells 20, re station box, loop l, and electric motor 25 are al1 continuously supervised by the half-waves of supervisorycurrent that are transmitted'through these circuits by the first half-wave recsifier HWRI. This half-wave supervisory current is not adequate to cause rotation of the synchronous or shaded pole motor 25. However, as soon as one of the sets of contacts I4 of one of the ire stations FSl--FS4 is closed, the two half-waves or complete cycles of the alternating current are transmitted to the electric motor 25 and this motor starts operating. The operating cycle then carries on through to completion in substantially the same manner described above in connection with Figure l.

Referring now to the different manner of controlling the control relay D embodied in Figure 2, it will be seen that normally the winding 32 is de-energized by reason of conductor 30 being open-circuited at reset contacts 50. However, in a signalling operation, consequent upon the closing of one of the sets of contacts I4 in one of the fire station boxes FSI-F84. the operation of the code wheel promptly closes the reset contacts and thereupon the complete cycle of the alternating current is transmitted from the shunted box loops l5-I 6 through the relay winding 3'2 yand reset contacts 50. The resulting en ergization of the relay D closes the holding contacts D2 so that the relay can be held energized by the half-wave current which the second rectiier HWR2 permits to pass over the holding circuit 54. It will be noted that the phase or polarity of the half-waves thatthis second rectifier HWR2 permits to pass over the holding circuit 54 is opposite to the phase or polarity of the supervisory current that the first rectifier HWRl permits to pass over the box loops and iire bell circuit. Hence, when the contacts I4 in Ithe Yfire station box FSl-Fsd are again opened, following the sounding of the four rounds of re alarm code signalling, the stopping of the motor 25', and the opening of the reset contacts 50, the supervisory half-wave current passing through rectier HWRI is blocked from passing over the holding circuit 54 by the oppositely facing blocking rectifier HWR2 and hence the hol-ding circuit is rendered non-eiective to hold the relay D energized. Accordingly, this relay D is immediately cie-energized and the system resumes its normal supervised condition. For example, halfwave supervisory cur-rent passing from the halfwave rectifier HWRI over the lbell circuit 2 l-23, would otherwise tend to flow down through motor circuit 24 and motor 25 and back up Aover conductor 35 to the top of relay winding v32 and thence out over holding circuit 54 for keeping this relay locked up, if it were not for the blocking action of the oppositely facing rectifier HWR2, which prevents the supervisory half-waves from rectifier HWRI taking this path down through the motor circuit and thereby locking up the relay D. Similarly, in Figure l, the location of the second half-wave rectifier HWR2 in conductor 35 and facing in a downward direction prevents the half-wave supervisory current from the rst rectifier HWRI passing down through the motor circuit and up over conductor 35 for locking up relay D over holding circuit 54, after the contacts I4 in the operated re box have been restored to open position for the purpose of restoring theV system t0 its normal supervised condition. Ihe third pair of contacts D3 of control relay D cl-ose with the initial energization of the control relay and continue sounding an alarm as long as said relay remains energized, i. e. until the operated fire station FSI-FS4 has been reset to normal by the opening of its contacts I4 and the replacing of its glass.

The milliammeter 29 need not necessarily be connected in the circuit at the point shown in Figures l and 2. It can be connected in the circuit at other points Where it is capable of giving a supervisory indication of the supervisory current flow. For example, it might be connected between the alarm relay A and the rst half# wave rectier HWRI, as shown in Figure 3. The synchronous or shaded pole motor 25' of Figure 2 can, of course, be employed in Figure l in lieu of the series motor 25, and, if desired, the embodiments of Figures 2 and 3 may have the second rectifier HWR2 located in conductor 35, as shown in Figure l, instead of in conductor 54.

Since certain further changes can be made in the foregoing system and different embodiments of the invention can -be made without departing from the spirit'and scope thereof, it is intended that al1 matter shown in the accompanying drawasc-asse andi' clescribed hereinbefore: sha-ll! be inten* preted asiillustrativeeand not inf af. li-initingr'sensei.

Whatnisclaimedlasnew is-a.

Inia: closed-.circuitimastercode'i'lrealarm system; arranged; forenergizationflrfiom :if-source of alternatingy current one..A terminal ofi" whichi is grounded., incombi'nation; a=-rstllialt Waverecti` erfconnectedtotheungroundedterminalofisaid source of!" alternating current; aplurality of" iireA bellseach` having' a windingy aV motor; circuit means connectingftheaforesaidlelementsfinseries circuit relation ini the order' named anx:l"t"o'A said groundedv terminalof'rsaid sourcei off' alternating current; a codewheel driven'by-"sa-idtmotbna plu# rality of 'ref-stationseaichhaving' apair of nor-Y mall'y` open contacts one of which: is connected"v to said" ungrounded" terminali` a secondla half" wave recti'er connected' in'series` with said* otliencontact'sy of said; fire stations andl to4 said grounded' terminal" of said* source` of alternating current' a control" relay; havingl normally closedi contacts connectedbet'ween the junction between saidre bellf windings andi said motor and the; oth'er'contacts: of saidii're stationsgand a.windingc'onnectl ed"b;etw.een`said` second halfgwaveV rectifier' and reset contacts responsive to saidfcode wheel: signalling contacts operated' by said! code wheel'. and connected'between the junction. between; said first halfjwaverectiiier andsaidie bell ,windings and said" groundedi terminal ofLsaidsourceLofalternating`- current', foi: energizing said.windngs. of saidiire bells, andl'contacts.. arrangedltfo be. closed onioperationA of"said.coderwlieell to maintain said motor. energized for. acompleteeyclaof .operation of saidlcode wneehsaidiirstland, second lhal'flwave rectifiers-being connectedgsa as) to conduct the same halt. wave.. oi` alternating. currentwhereby said. winding of. said.v control, relay. normally re.- mains. cle-energized,v theclosure of any. setloi nre stationn contacts -`completingvv an` energizing.y circuit through tsaid. control` relay contacts to energize said motor. suiliciently.v to, drive.-v said,y code: wheel and` energize. said 're bells and1 to.. apply` half waves ...of, opposite.. polarity.. to. said., control. relay winding to energize` the,same,and`op,en.its con.- tactsther.eb'{` preventing.;operationiof` saidseries motori*andcod'e;.wheel;b.eyond.a complete. cycleof operation. of the..latter.

2'. In a. closedcirxcuit` master oodedirealarm system arranged.A for, energization. from a. .source of alternating.; current one4 ,terminalgot whic'iris grounded-, .andihaying annuxiliary. power source, in combination,` vaafirst alarmrela-y having a-.windf ing: connected tothe tungrouncled...terminallof` said source, of g alternating; current, a4` rst half.. wave rectifier, a.u pluralityr on, fire. bells.; each.- having. a winding, an alternating, current. motori, circuit means` connectinggthe ,aforesaid elements;v in `series circuiti relation in., the order namedl and... toI said grounded terminaLof.; saidource of: alternating current,. aj, plurality., ot' iireev-istations.- each hav-ing alpair, of normally` onenicontacts one .,of.. which v:is connectecLto=said,ungrounded terminal, asecond ala-rmlnelayfhaying aswinding. connectedlto each of; the.- other. contactant.. said .vi-lre.b stations,f.a,..sec= ond;` halfJV waive rectiiierY connectedAr infseries .with saidwindingAi oi-l. saidv second:v alarm relay, and to said grounded terminal offsaid soi-irceoi alternat-4 ingV corre/nm. an control-.. relay hay-ing;1 normally closed@ contactsaconnected betweenl `tlie.Junction betweenYr said iire f bell 1 windings and f said motorv and thefjunction-i between the other: contacts-lof saidireffstationsiand said windinguotsaid second alarm ,reiayf-,a-nd.. a. relay winding.; connected between safid secondhalfa wave:- rectifier.l annifE Said' lilV grounded' terminal; a codawheel;` driven. byV said motor, contacts operated: bly said'y code wheelv and connected between the junction between saidrst half wave rectifier and saidfire belliwindings and= said groundedterminal of said source of alter nating current for energizing" said windings ot said'iire. bells, aset of contacts normally heldop'env by each winding of each of said alarrnrirelaysiandl arranged" to4 complete an alarm circuit energized from said auxiliary power'source onL de-e'riergiza.-A tion of any of said alarm' relay windings, andc'on tacts` arranged to be' closed on operationiof said code wheel to maintain Saidmotor energized fori a complete' cycle of operationof said code' wheel,l saidr firstand' second' hal'f-V wave rectiiiers be'ing connectedso as to-condiict-the-sanie halt wa've'oi alternating current whereby sai-'dv winding oisaid-V control relay normally' remains de'energize'd,` the? closure of vany set ofreistationcontactscompleting an energizing circuitv through said-controllo?- layacontacts to energize1 said motorsuiciently'to drive said code wheel andH energize said nre'- bells`v and to apply half waves of opposite` polarity to said' control relay' windingV to energize'lthe same and open its contacts thereby preventing' oper'a'e tion' of said motor andcode'wheel beyond'E acorn-f pletecycle of' operation offt'helatter.-

3. In a closed' circuit master code r'e' alarm system arranged for'energiZation"y from' a`- source of valternating currentV one terminal of`wli'ic1- is groundedv and having an auxiliary power" source; inA combination, a nrst'alarm* relay having'a'higli impedance winding connected to the 'unglrounde'd terminal otsaid'sourlseoi" alternating' current; a i'llst half wave rectifier; av plurality of-'re bells each having a winding; a seriesmotor; a" second alarm relay having a"v low: impedancev winding, circuit means connect-ing the aforesaidV elements in series circuit'` relation in thelorder` Iiamed and toV said'- grounded' terminal ofL said' source of? al'- ternating current, aL plurality oiy nre stations eacli having aY pair ofnormallyv open'- contacts'fv one of which i's connected to saidy ungrounded" t'e'rniinal,` a third relay having a-win'ding` connectedt'oeach of'the-othercontacts ofs'aidfirestations; a-se'cond hali'wave rectifier connected in series` with said winding o'f` said third alarmrelayI andI toy said grounded termina-l'y ofsa'id source; off alternating current; a control: relayv having'` normally' close'd contacts [connected: between the junction between saidv iireloellA windingsv andsaidV series lmotor and the" junctionV betweenA the other contacts of vsaid re stations andz said windingv of said third i'al'arrn relay, and a relayfwindingconnected betweenltlie' other contacts of Asaid re4 stations andsaid grounded' terminal; a code' Wheel driven` byA saidl series motor, contacts onerat'edbys'aid code-wheel and connecte'd'between-the junctionibetween said iirstv half wave rectifier" and said ii'ret Idellwind# ings and said vgrounded terminalfof'saidl sourcec'f alternating current forY energizing said windings of said nre bells; a setof' contacts' normally'hcld open by each` winding'of-i each of' saidvalarr'n ree' lays and arranged to complete 'an alarm circuit energized from said Vauxiliarypower-"source on'del' energization" of' anyof saidialarrnrelay windings, and;l contactsarranged to" 'oeclosed on" operation of saidcode wlieelto maintain saidseiiesniotoi' energizedjforfa.complete cycl'eofoperationrof said code wheelsaidl`rst .and second `half-'wave resti# ers being connectedso. as to. conduct the same half. wave of alternating currentA whereby said winding-fof 1said. control.relay-normallyfremains deenergized, the; closure of any' seti ofrvii-re-station contacts .completing lanienergizing-circuit through said control relay contacts to energize said series motor suiiiciently to drive said code wheel and energize said nre bells and to apply half waves of opposite polarity to said control relay winding to energize the same and open its contacts thereby preventing operation of said series motor and code Wheel beyond a complete cycle of operation of the latter.

4. In a closed circuit master code fire alarm system arranged for energization from a source of alternating current one terminal of which is grounded and having an auxiliary power source, in combination, a first current limiting resistor connected to the ungrounded terminal of said source of alternating current, a rst alarm relay having a winding, a rst half wave rectifier, a second current limiting resistor, a plurality of lire bells each having a winding, an alternating current motor, circuit means connecting the aforesaid elements in series circuitrelation in the order named and to said grounded terminal of said source of alternating current, a code wheel driven by said motor, reset contacts responsive to said code wheel, a plurality of fire stations each having a pair of normally open contacts one of which is connected to said first resistor, a second alarm relay having a winding connected to each of the other contacts of said fire stations, a second half Wave rectier connected in series with said winding of said second alarm relay and to said grounded terminal of said source of alternating current; a control relay having normally closed contacts connected between the junction between said fire bell windings and said motor and the other contacts of said i'lre stations and a relay winding connected at one end to said second half wave rectifier and at its other end connected through said reset contacts with said grounded terminal, a code wheel driven by said motor, signalling contacts operated by said code wheeland connected between the junction between said first half wave rectifier and said second resistor and said grounded terminal of said source of alternating current for energizing said windings of said nre bells, a set of contacts normally held open by each winding of each of said alarm relays and arranged to complete an alarm circuit energized from said auxiliary power source on de-energization of any of said alarm relay windings, and contacts arranged to be closed on operation of said code wheel to maintain said motor energized for a complete cycle of operation of said code wheel, said rst and second half wave rectiers being connected so as to conduct the same half wave of alternating current whereby said winding of said control relay normally remains de-energized, the closure of any set of fire station contacts cornpleting an energizing circuit through said control relay contacts to energize said motor suiiiciently to drive said code wheel and energize said fire bells and to apply half waves of opposite polarity to said control relay winding to energize the same and open its contacts, thereby preventing operation of .said motor and code wheel beyond a complete cycle of operation ofthe latter.

5. In a closed circuit master code re alarm system arranged for energization from a source of alternating current one terminal of which is grounded and having an auxiliary power source, in combination, a first current limiting resistor connected to the ungrounded Aterminal of said source of alternating current, a iirst alarm relay having a high impedance winding, a first half wave rectifier, a second current limiting resistor, a plurality of fire bells each having a winding, an alternating current motor, a second alarm re- 12 lay having a lowimpedance winding, circuit means connecting the aforesaid-elements in series circuit relation in the order named and to said grounded terminal of said source of alternating current, a plurality of nre stations each having a pair of normally open contacts one of which is connected to said first resistor, a third alarm relay having a winding connected to each of the other contacts of said fire stations, a second -half Wave rectifier connected in series with said winding of said third alarm relay and to said grounded terminal of said source of alternating Y current; a control relay having normally closed contacts connected between the junction between said re bell windings and said motor and the junction between the other contacts of said re stations and said winding of said third alarm relay, anda relay winding connected between said second half Wave rectifier and said ungrounded terminal, a code wheel driven by said motorfrcontacts operated by said code wheel and connected between the junction between said first half .wave rectifier and said second resistor and said grounded terminal of said source of alternating current for energizing said windings of said re bells,l a set of contacts normally held open by each winding of each of said alarm relays and arranged to complete an alarm circuit energized from said auxiliary power source on de-energization of any of said alarm relay windings, and contacts varranged to be closed on operation of said code Wheel to maintain said motor energized for a complete cycle of operation of said code wheel, said first and second half wave rectiers being connected so as to conduct the saine half wave of alternating current whereby said winding of said control relay remains de-energized, the closure of any set of re station contacts completing an energizing circuit through said control relay contacts to energize said motor su'iciently to drive said code wheel and energize said fire bells and to apply half waves of opposite polarity to said control relay winding to energize the same and open its contacts thereby preventing operation of said motor and code wheel beyond e complete cycle of operation of the latter.

' 6. In a closed circuit master code fire alarm system of the class described, the combination.

with an alternating current supply circuit, one side of which is grounded, of a plurality of iire stations, rst and second conducting loops between which said re stations are connected in parallel, one of said loops being energized from one side of said alternating current supply circuit, an alternating current motor connected to be operatively energized from said alternating current supply circuit in response to an interconnection being established between said loops through one of said fire stations, a code wheel driven by said motor, signalling contacts responsive to said code wheel, a signal circuit adapted to be energized with signalling impulses from said alternating currentv supply circuit through said signalling contacts, fire bells responsive to said signal circuit, a control relay for controlling the stopping of said motor after al predetermined signalling cycle, 'trouble relays supervising said re station loops, signal circuit and motor, and rectifier means connected with said conducting loops, signal circuit and motor whereby one half of the `alternating current wave from said supply circuit is utilized for supervision of said conducting loops, signal circuit and motor, and the full wave for signalling operation of said motor and fire bells.

'7. In a system of the class described, the combination with an alternating current supply cirattacca'- 1&3.r cuitrof" llrstzand; second.y fire e' station-iloops;L -saidrst lmipbeingv connected withff-one sidefof said-1 supply circuit; a pluralit/' ol;fre4 stations fingbridginggrelation rbetween: said loops; asignallingcir.- cuit;connected -with said7 niirst'` loop-,I refcbells in. terposed; in series` in` said: signalling circuit,v al motorycircuit connect/edi betweenV said 1 signalling circuitand'thefother"side Lof said qsupplycircuit, am a-lternating-.- current tmotor Vinterposed `in said motory c-ircuit,f,acodefwheel driven by .said motor; signalling;contacts?responsive3 thereto-for trans-A mitting signalling impulsesfto :said signalling cir-` cuit-from asaid 'supply circuit, full'A cycle-contacts controlling said code-whee1, reset contacts rez-f sponsive toL said -code W-l1eel,A acontrol ,frelay com. prising` a-,Windingfand main contacts, said main contacts Vconnecting saidv motor 'circuitswith said second firstfstationloom.and an control-circuit extending`` from l said.7 second. re station;Y loolo through-:said :control trelic. y. winding; and said.A re-v. set@I contactsmtof the. other; side` of said'- supply circuit. v

8 In aclosed.fy circuitnmaster, code, lire .alarm system arranged for energization `fromlanalternatingcurrent .supply line,.one,side1 of "Whichnslay bagrounded, Vthe,combination.ofc rstandsecond fire, stationlloop,conductors., aiplurality, ofY lira stationsiconnected iniibridlging,v relation between saidloop;.co:o,olucto1ts, ar signalling` circuit, signal.- ling: bells ,interposed im seriesiin ,sali signalling`- circuit,.- acontrol relayYcomprisingwindinggand normality closed, contacts,. circuiti, crmnections.l establishingc a normally;- closed supervisory? cire cutiextending, from ,oneside ,ofsaidalternatingl currentsupplyn line througnsaid iirst` fire5r staf:- ti'on -loopfconducton signallingy circuitnnormallyA closedA control relayY contacts, andi second; fire station loop' conductor. in series4 1an,Cllltllen-ceil to5 the otherside oisad.alternatinggcurrentlsunply line, arralarm. relay` responsive to. said`- supervisoryz circuit, a motortcircuit'connected.between sadsupervisory circuitLandgthelattenside ofsaidj alternating currellt.;supply,Y linea. an alternating current; motor. inisaid" motor circutg, rectier; means saidlsytern v,for limiting the flow of*` supelivisoryI current'tlirougli saidjsupervisory` .cincuit andlthrougli said motor circuitto l'ralffgwave current; said re' stations comprisingI contacts adaptediupon rejstation operation torestablish a l loriglging ,relation between said loop .conductors for transmitting f fullewave alternating current to .said `Ymotoraa code Wheel driven'bysaid motor', signalling lcontacts actuated bx said` code wheel connected for ytransnlittingY alternatingk current' signal; pulses 'over said signalling circuitl to* said. signalling ,bells in aV signallingjoperationgand' cyclical controlmeans vincludingrsaid ,controlrelay Winding and'j contacts responsive; to1motoriopf eration for" controlling-the length off the Vsignallngoperation;

9;"I`n afclosed circuit; master code'V fref alarm system arranged* for Aenergization-` from an4 aliternating current supply line: on eside'of-wliiclr may bei grounded? tl'ie-v comb ination-ofI first and secondref stationn loop conductors; af pluralityV oire stations connected inA lniclging relationbetween saidjloop conductors, a' signalling'ycir` cuit, .signalling Abells"interposed 'in series in Nsaid signalling., circuit, aV control-.relay, comprising a` Windingtk and.l normally; closed contacts,A circuit connections. establishing, a,v normally. closed su-- pervisoryt-circuitextending Afrom-oneside ofisaid alternating. current rsupply .linethrough Asaid first -re-stationloop conductor; signalling;. circuit,- Inerf-'- malls/closed control relayffcontaci-sr ranch second 14T reastaitioncloopsconductopimseriesianthencef tozithe -other sides of said; alternating;Y currentsupnly line; an alarmzrclay responsive to-saidf supervisory-circuit; a motor: circuit connected betweenw said supervisory circuit andthe latten; sideof,fsaidfalternating-current supplyfline, :analeternatingN currentV motor@ in said ,motorf circuit,y a; secondil alarm, relay,- responsivev to f, said f motor.,

circuit; Iectiferjmeans innsaidsystem zffor; limiting? visorygl circuit through the Windinggof rsaid.. corkF trol relay;r tofthe. other, sider of 1 saidalternatingEv current supply-lineresety contacts aresphonsiveftoi said@ code-;Wlleel-,-fori closing, -said-r` normally;- open.'A relay circuit, and i full cycle- `contacts connected I between saidumoto-r; circuiti and said supplyycin-jcultiand.iresponsiveeto:motor-foperationfor comA trolling-gthe@lengthfiof theignalliriggoperation;A

19.,.@1 -Laicloseclacircuii-I, mastercode re alarm systemffarranged forfenergization .ffrom an-faltevr,A natingfcurrent simply lincgnonesideofawhichfmafyf befrfggr oundedythef ccmibinationof:r first vand second; fire station loop conductors, a pluralityfof rer 'stationsfv connected-A inebridging relationy between saide.loopgconductorsga-,signallingfc-ircuit; signa/lf' lingfbells-lfinterposed, in seriesf-in ftsaid :signalling circuit; control#L relay.toomprisingganwinding, and. ncrmallyaclosed; contacts, circuit connectionsL establishingamormallyf-closed :supervisory circuit; extendingffromone aside, fof saidl alternating;,cur;

rentsugpl -lineftlo'rouglrsaidQilrstlirestatiorrloop t conductor,- signalling-acircuit;y normally:k closedcontrol relay? contacts#` and secondare stationlooprconcluctor-,yinPscriesfandrfthence-ctofthegotherff sidesi -ofsaid;- alt-ernating; current' supply f-lineg- "ai superv isorygalarmrrelay;interposedrin said-super. vi-sffny,fcircuit,betivveen` said first iirei'station-f1oopv conductor and'said: signallingcircuit, aimotoncircuitaconneotedvto: said' sup ervisory circuit .at a pointnbetweerrsaintsignallingfcircuitrandsaidmoni mallyeclosedcontrol frelayncontacts --and extendingA toztireotherisideiof'ssai dalternating currenfasi-ip-t plyif circuiti. am alternating f'curre'ntemotorvinfsaid motori circuiinfaJ motor: supervisory; alarmerelafy"r responsii'eato: saidcmotor circuit-gs rectier, -means`v innsaid supervisory circllitibetweensaiclrstres` station-f. loopt.:4 conducto-rc and.'-V said@ signaliin gif cir-e'- cuittfonfliinit fgifrtl'iealoWi-of superlvisory'fcurrentv tnrouglrzsaid :supervisory circuit sand through said',` motorfcircufit to.::lralrWart-3scurrent;l a-supervisory'a alarmerelaf;connectediinfsaidsupervisorycircuit between-sazidrsecondr'ire station zloo1o:.=concluctorl andther; otl'i'er;v 'side-If offsaioly alternating: current'` supplyrfline, acrrorrnallyf'open;relayficircuit'v extend/'-4 ing; from ,said supervisory# circuitV tlirougl'lff the'v windingfof saiolfz.controla:relayfv to: the other side@ offsaid-alternati-ng ,lcurrentsupply flinesaid fire:A

7o? stations comprising ,contactsfadaptedf uponffre stationtopjerationetotestablisli'n a .bridging relation between saclf.loo-p5.I conductors. for@ transmitting: v

f ulliiW-avef` alternating? current?.tersa-id"-l motorai @colei/.Wheel drivenibycsaid'irnotory 'signalling'rconf-e 7-51tactseactuatedgbyf-said:codeevrheelaandfconnecteota between said signalling circuit and the other side of said alternating current supply line for transmitting full-wave alternating current signal pulses over said signalling circuit to said bells in a signalling operation, reset contacts responsive to said code Wheel for closing said normallyv open relay circuit, and full cycle vcontacts responsive to operation of said motor for connecting said motor circuit directly to the first named side of said alternating current supply line.

11. In a system of the class described arranged for energizaticn from an alternating current supply line, one side of which may be grounded, the combination of an alarm station circuit comprising parallel conductors and a plurality of alarm stations having alarm contacts therein adapted to establish a shunt connection across said parallel conductors, a bell circuit having a plurality of `bells therein, a motor circuit having a motor therein, circuit connections including rectifier means for normally transmitting half-Wave supervisory current from s aid alternating current supply through said alarm station circuit, bell circuit and motor circuit, resistor means for limiting the current flow through said circuits in the event of inadvertent grounding, means whereby the operation of one of said alarm stations transmits full-wave alternating current from said alternating current supply line to said motor, signalling contacts responsive to said motor for transmitting 4alternating current signalling pulses from said alternating current supply line to said bell circuit, and means for automatically controlling the duration of the signalling operation. f

' 12. In a system of the class described arranged for energization from an alternating current supply line, the combination of an alarm station circuit comprising alarm stations having alarm contacts therein, a bell circuit having bell means therein, a motor circuit having a motor therein, circuit connections including rectifier means for 'normally transmitting half -Wave supervisory current from said alternating current supply line through said alarm station circuit, bell circuit and motor circuit, means whereby the operation of one of said alarm stations transmits full-Wave alternating current to said motor, andsign-alling contacts responsive to said motor for transmitting signalling pulses to said bell circuit. Y

13. In a system of the class described arranged for energization from an alternating current supply line, the combination of an alarm station circuit comprising-alarm stations having alarm contacts therein, a bell circuit having bell means therein, a motor circuit having a motor therein, a control relay responsive to said alarm station circuit for controlling said motor, circuit connections including rectier means for normally transmitting half-wave supervisory current from said alternating current supply line through said alarm station circuit, said bell circuit and said motor circuit, means whereby the operation of one of said alarm stations transmits full wave alternating current to said motor, signalling contacts responsive to said motor for transmitting signalling pulses to said bell circuit, a holding circuit for said control relay, and second rectifier means in said holding circuit for governing said control relay. i

14.,In a system of the class described arranged for energization from an alternating current supply line, the combination of an alarm station circuit comprising alarm stations having alarm contacts therein, a bell circuit having bell means therein, a motor circuit having a motor therein, a control relay responsive to said alarm station circuit for controlling said motor, circuit connections including rectifier means for normally transmitting half-wave supervisory current from said alternating current supply line through said alarm station circuit, said bell circuit and said motor circuit, means whereby the operation of one of said alarm stations transmits full wave alternating current to said motor, signalling contacts responsive to said motor for transmitting signalling pulses to said bell circuit, and a trouble circuit including contacts responsive to said control relay for sounding a trouble alarm while said control relay remains energized. 15. In a system of the class described arranged for energization from an alternating current supply line, the combination of an alarm station circuit comprising alarm stations having alarm contacts therein, a bell circuit having bell means therein, a motor circuit having a motor therein, a control relay responsive to said alarm station circuit for controlling said motor, circuit connections including rectifier means for normally transmitting half-wave supervisory current from said alternating current supply line through said alarm station circuit, said bell circuit and said motor circuit, means whereby the operation of one of said alarm stations transmits full wave alternating current to said motor, signalling contacts responsive to said motor for transmitting signalling pulses to said bell circuit, a holding circuit for said control relay, second rectier means in said holding circuit for governingrsaid control relay, and a trouble circuit including contacts responsive to said control relay for sounding a trouble alarm while said control relay remains energized.

16. In a system of the class described arranged for energization from an alternating current .supply line, the combination of an alarm stationvcircuit comprising alarm stations having alarm contacts therein, a bell circuit having` bell means therein, a motor circuit having a motor therein, a control relay responsive to said alarm station circuit for controlling said motor, circuit connections including rectifier means for normally transmitting half-Wave supervisory current from said alternating current supply line through said alarm station circuit, said bell circuit and said motor circuit, means whereby the operation of one of said alarm stations transmits full wave alternating current to said motor, signalling contacts responsive to said motor for transmitting signalling pulses to said bell circuit, and full-cycle contacts governing said motor for producing a predetermined signalling cycle by said signalling contacts, said motor being of an alternating current type requiring both waves of the alternating current for its operation so that it does not respond to said half-Wave supervisory current.

17. Ina system of the class described arranged for energization from an alternating current supply line, the combination of an alarm station circuit comprising alarm stations having alarm contacts therein, a bell circuit having bell means therein, a motor circuit having a motor therein, a control relay responsive to said alarm station circuit for controlling said motor, circuit connections including rectifier means for normally transmitting half-wave supervisory current from said alternating current supply'line through said alarm station circuit, said bell circuit and said motor circuit, means whereby the operation of one of said alarm stations transmits full wave alternating current to said motor, and signalling contacts responsive to said motor for transmitting signalling pulses to said bell circuit, said motor being of an alternating current type requiring both alternations of the alternating current for its operation so that it does not respond to said half-Wave supervisory current.

18. In a system of the class described arranged for energization from an alternating current supply line, the combination of an alarm station circuit comprising alarm stations having alarm contacts therein, an electric motor responsive to said alarm station circuit, signalling contacts responsive to said motor, agbell circuit hav-- .ing bell means therein responsive to said signalling contacts, means for transmitting less than the full wave of said alternating current supply line over the system and through said motor during non-signalling intervals for superl0 vising the system, and means for transmitting 18 the full wave of said alternating current supply line to said motor during signalling intervals.

19. In a system of the class described arranged for energization from anralternating cur- REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number 

